Torch igniter for a combustor

ABSTRACT

An igniter for a combustor of a turbomachine includes a fuel inlet in fluid communication with a mixing plenum. The mixing plenum is positioned upstream of a mixing channel. An air inlet is in fluid communication with the mixing plenum and an ignition source is in operative communication with the mixing channel. The igniter may include a mounting flange configured for coupling the igniter to the combustor. The ignition source may be positioned proximate to a downstream end of the mixing channel and upstream of the mounting flange. The mixing channel may define a venturi shape. The venturi shape includes a converging section between an upstream end of the mixing channel and a venturi throat.

FIELD

The present disclosure generally involves an apparatus for igniting acombustor of a turbomachine.

BACKGROUND

Gas turbines, aircraft engines, and numerous other combustion-basedsystems include one or more combustors that mix a working fluid such asair with fuel and ignite the fuel-air mixture to produce hightemperature and pressure combustion gases. For example, commercial gasturbines may be used for generating power. A typical gas turbine used togenerate electrical power includes, in serial flow order, a compressor,a combustor and a turbine. Ambient air may be supplied to thecompressor, and rotating blades and stationary vanes in the compressorprogressively impart kinetic energy to the working fluid (air) toproduce a compressed working fluid at a highly energized state. Thecompressed working fluid exits the compressor and flows through one ormore nozzles where the compressed working fluid mixes with fuel and thenflows into a combustion chamber in each combustor where the mixtureignites to generate combustion gases having a high temperature andpressure. The combustion gases expand in the turbine to produce work.For example, expansion of the combustion gases in the turbine may rotatea shaft connected to a generator to produce electricity.

The combustion may be initiated by an ignition system in one or morecombustors. The ignition system may produce a spark or other source ofignition, e.g., a laser beam or pilot flame, inside of the combustor.

The ignition system is often located along a side of the combustionchamber so that the ignition system may project the spark, beam, orflame into the combustion chamber approximately coincident with thefuel-air mixture. The location of the ignition system along the side ofthe combustion chamber requires a penetration through the liner of thecombustor, creating a potential source of leakage and/or turbulent flowthrough or around the penetration. In addition, ignition systems locatedalong the side of the combustor necessarily interfere with the flow ofthe working fluid between the liner and the flow sleeve, therebyincreasing the differential pressure of the working fluid across thecombustor which decreases the overall efficiency of the gas turbine.Such configurations may result in reduced amount and/or flow rate ofworking fluid available to mix with the fuel in the nozzles. The amountof working fluid available for premixing with fuel has a direct impacton the peak flame temperatures and NOx emissions.

The ignition system may include an ignition torch. The ignition torchmay receive a flow of fuel and a flow of air. The air and fuel may mixin the torch and be ignited by an ignition source, such as a spark plug,in order to provide a pilot flame to initiate combustion in thecombustion chamber. The spark plug is typically located proximate to thecombustion chamber.

BRIEF DESCRIPTION

Aspects and advantages are set forth below in the following description,or may be obvious from the description, or may be learned throughpractice.

According to one embodiment, a gas turbine is provided. The gas turbineincludes a compressor, a turbine, and a combustor disposed downstreamfrom the compressor and upstream from the turbine. The gas turbine alsoincludes an igniter in operative communication with the combustor. Theigniter includes a mixing channel defining a venturi shape. The venturishape includes a converging section between an upstream end of themixing channel and a venturi throat. The igniter also includes a fuelinlet in fluid communication with a mixing plenum. The mixing plenum ispositioned upstream of the mixing channel. The igniter also includes anair inlet in fluid communication with the mixing plenum and an ignitionsource in operative communication with the mixing channel. The ignitionsource is positioned downstream of the mixing plenum.

According to another embodiment, an igniter for a combustor of aturbomachine is provided. The igniter includes a mounting flangeconfigured for coupling the igniter to the combustor. The igniter alsoincludes a fuel inlet in fluid communication with a mixing plenum. Themixing plenum is positioned upstream of a mixing channel. The igniteralso includes an air inlet in fluid communication with the mixing plenumand an ignition source in operative communication with the mixingchannel. The ignition source is positioned proximate to a downstream endof the mixing channel and upstream of the mounting flange.

According to yet another embodiment, an igniter for a combustor of aturbomachine is provided. The igniter includes a mixing channel defininga venturi shape. The venturi shape includes a converging section betweenan upstream end of the mixing channel and a venturi throat. The igniteralso includes a fuel inlet in fluid communication with a mixing plenum.The mixing plenum is positioned upstream of the mixing channel. Theigniter also includes an air inlet in fluid communication with themixing plenum and an ignition source in operative communication with themixing channel. The ignition source is positioned downstream of themixing plenum.

Those of ordinary skill in the art will better appreciate the featuresand aspects of such embodiments, and others, upon review of thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of various embodiments, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures, in which:

FIG. 1 is a functional block diagram of an exemplary gas turbine thatmay incorporate various embodiments of the present disclosure;

FIG. 2 is a simplified side cross-section view of an exemplary combustoras may incorporate one or more embodiments;

FIG. 3 is a side cross-section view of an exemplary igniter according toone or more embodiments of the present disclosure;

FIG. 4 is an end view of the exemplary igniter of FIG. 3 ;

FIG. 5 is a side cross-section view of an exemplary igniter according toone or more embodiments of the present disclosure;

FIG. 6 is a side cross-section view of an exemplary igniter according toone or more embodiments of the present disclosure;

FIG. 7 is a side cross-section view of an exemplary igniter according toone or more embodiments of the present disclosure; and

FIG. 8 is an end view of the exemplary igniter of FIG. 7 .

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of thedisclosure, one or more examples of which are illustrated in theaccompanying drawings. The detailed description uses numerical andletter designations to refer to features in the drawings. Like orsimilar designations in the drawings and description have been used torefer to like or similar parts of the disclosure.

As used herein, the terms “first,” “second,” and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.The terms “upstream” and “downstream” refer to the relative directionwith respect to fluid flow in a fluid pathway. For example, “upstream”refers to the direction from which the fluid flows, and “downstream”refers to the direction to which the fluid flows. The term “radially”refers to the relative direction that is substantially perpendicular toan axial centerline of a particular component, the term “axially” refersto the relative direction that is substantially parallel and/orcoaxially aligned to an axial centerline of a particular component, andthe term “circumferentially” refers to the relative direction thatextends around the axial centerline of a particular component.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” and/or “comprising,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

Each example is provided by way of explanation, not limitation. In fact,it will be apparent to those skilled in the art that modifications andvariations can be made without departing from the scope or spiritthereof. For instance, features illustrated or described as part of oneembodiment may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present disclosure covers suchmodifications and variations as come within the scope of the appendedclaims and their equivalents.

Although exemplary embodiments of the present disclosure will bedescribed generally in the context of a land based power generating gasturbine combustor for purposes of illustration, one of ordinary skill inthe art will readily appreciate that embodiments of the presentdisclosure may be applied to any style or type of turbomachine and arenot limited to land based power generating gas turbines unlessspecifically recited in the claims.

Referring now to the drawings, FIG. 1 illustrates a schematic diagram ofan exemplary gas turbine 10. The gas turbine 10 generally includes aninlet section 12, a compressor 14 disposed downstream of the inletsection 12, at least one combustor 16 disposed downstream of thecompressor 14, a turbine 18 disposed downstream of the combustor 16 andan exhaust section 20 disposed downstream of the turbine 18.Additionally, the gas turbine 10 may include one or more shafts 22 thatcouple the compressor 14 to the turbine 18.

During operation, air 24 flows through the inlet section 12 and into thecompressor 14 where the air 24 is progressively compressed, thusproviding compressed air 26 to the combustor 16. At least a portion ofthe compressed air 26 is mixed with a fuel 28 within the combustor 16and burned to produce combustion gases 30. The combustion gases 30 flowfrom the combustor 16 into the turbine 18, wherein energy (kineticand/or thermal) is transferred from the combustion gases 30 to rotorblades (not shown), thus causing shaft 22 to rotate. The mechanicalrotational energy may then be used for various purposes such as to powerthe compressor 14 and/or to generate electricity. The combustion gases30 exiting the turbine 18 may then be exhausted from the gas turbine 10via the exhaust section 20.

As shown in FIG. 2 , the combustor 16 may be at least partiallysurrounded by an outer casing 32 such as a compressor discharge casing.The outer casing 32 may at least partially define a high pressure plenum34 that at least partially surrounds various components of the combustor16. The high pressure plenum 34 may be in fluid communication with thecompressor 14 (FIG. 1 ) so as to receive the compressed air 26 from thecompressor 14. An end cover 36 may be coupled to the outer casing 32. Inparticular embodiments, the outer casing 32 and the end cover 36 may atleast partially define a head end volume or portion 38 of the combustor16.

In particular embodiments, the head end portion 38 is in fluidcommunication with the high pressure plenum 34 and/or the compressor 14.One or more liners or ducts 40 may at least partially define acombustion chamber or zone 42 for combusting the fuel-air mixture and/ormay at least partially define a hot gas path 44 through the combustor,for directing the combustion gases 30 towards an inlet to the turbine18. One or more fuel nozzles 50 may be coupled to the end cover 36 andextend towards the combustion chamber 42. An igniter 100 may be inoperative communication with the combustor 16 and the igniter 100 may beconfigured to initiate combustion in the combustor 16. The igniter 100may extend axially downstream from the end cover 36. As used herein inthe context of the combustor 16, “axially” is with respect to an axialcenterline 46 of the combustor 16, e.g., the igniter 100 may extenddownstream from the end cover 36 along or parallel to the axialcenterline 46. In other embodiments, the igniter 100 may extend at anysuitable angle such that the igniter 100 is in communication with thecombustion chamber 42. For example, in some embodiments, the igniter 100may be oriented perpendicularly to the axial centerline 46.

As shown for example in FIG. 3 , the igniter 100 may include a mountingflange 122 configured for coupling the igniter 100 to the combustor 16.In some embodiments, the mounting flange 122 may include bolt holes 124for receiving bolts through the bolt holes 124 to fasten the igniter 100to the combustor 16. In particular, the mounting flange 122 may beconfigured for coupling the igniter 100 to the end cover 36 of thecombustor 16. In such embodiments, the igniter 100 may be coupled to theend cover 36 of the combustor 16 such that a central axis 130 of theigniter 100 may be generally parallel to the central axis 46 (FIG. 2 )of the combustor 16.

As may be seen, e.g., in FIGS. 3 and 4 , the igniter may include one ormore air inlets 104. In some embodiments, the air inlet(s) 104 may be influid communication with the head end 38 and positioned to receive aflow of compressed air 26 from the head end 38. In some embodiments,each air inlet 104 opens into a respective air conduit 106. Each of theair conduits 106 provides fluid communication between a correspondingair inlet 104 and a mixing plenum 110. As illustrated for example inFIG. 3 , a fuel conduit 108 may be in fluid communication with themixing plenum 110 via a fuel inlet 102. The mixing plenum 110 may bepositioned upstream of a mixing channel 112. Fuel 28 and air 26 may bemixed in the mixing plenum 110 and in the mixing channel 112 prior toignition by an ignition source 120. The ignition source 120 may be,e.g., a sparkplug. The ignition source 120 may be in operativecommunication with the mixing channel 112. In some example embodiments,the ignition source 120 may be positioned proximate to a downstream endof the mixing channel 112. As used herein, terms such as “upstream” or“downstream” are to be understood with reference to the flow directionof mixed fuel 28 and compressed air 26 within the igniter 100, e.g.,generally from the mixing plenum 110 towards the combustor 16, e.g., thedownstream end of the mixing channel 112 refers to an end of the mixingchannel 112 distal from the mixing plenum 110. In some embodiments, theignition source 120 may be positioned upstream of the mounting flange122. Such embodiments advantageously provide ease of access to theignition source 120 when the ignition source 120 is positioned outsideof the combustor 16 rather than proximate to the combustion chamber 42.

The mixing channel 112 may extend axially between the mixing plenum 110and an ejector tube 126. The ejector tube 126 may be positioneddownstream of the mixing channel 112. In particular, the ejector tube126 may be positioned downstream of the ignition source 126 to receivecombustion products, e.g., hot gases, generated upon ignition of themixed fuel 28 and air 26 by the ignition source 120. The ejector tube126 may extend into the combustor 16, e.g., through the end cover 36 toprovide a pilot flame to the combustion chamber 42. In some embodiments,the ejector tube 126 may optionally include a swirler 128 downstream ofthe ignition source 120. For example, as illustrated in FIG. 3 , theswirler 128 may be a ribbon swirler. Other example embodiments of theswirler 128 may include swirler vanes, turbulators, and the like.

As illustrated for example in FIG. 3 , in some embodiments, thecross-sectional shape of the mixing channel 112 may be constant, e.g.,the mixing channel 112 may be cylindrical. In other embodiments, themixing channel 112 may have other prismatic shapes, e.g., the mixingchannel 112 may be a rectangular prism, or may have other polygonalcross-section shapes such as but not limited to hexagonal.

In some embodiments the mixing channel 112 may define a plurality ofdistinct inner diameters. Generally, the mixing channel 112 may define afirst inner diameter portion 114 in an upstream portion of the mixingchannel 112, and may define a minimum inner diameter at a throat portion116 downstream of first inner diameter portion 114, and a second innerdiameter portion 118 downstream of the throat portion 116. The minimuminner diameter at the throat portion 116 may be less than the innerdiameter at the first inner diameter portion 114 or at the second innerdiameter portion 118. In various embodiments, the inner diameter at thefirst inner diameter portion 114 may be greater than or substantiallyequal to the inner diameter at the second inner diameter portion 118. Insome embodiments, for example, as illustrated in FIG. 5 , the pluralityof distinct internal diameters may form a venturi shape. As shown inFIG. 5 , the first inner diameter portion 114 may form a convergingsection 114 of the venturi shape, the second inner diameter portion 118may form a diverging section 118, and the throat portion 116 may thus bea venturi throat 116. In some example embodiments, the venturi shape mayinclude the converging section 114 between an upstream end of the mixingchannel 112 and a venturi throat 116. For example, the convergingsection 114 may extend between an end of the mixing channel 112proximate to the mixing plenum 110 and the venturi throat 116. Theconverging section 114 may include a section of the mixing channel 112wherein the cross-sectional area of the mixing channel 114 decreasesmoving axially downstream from the mixing plenum 110 to the venturithroat 116. Thus, the venturi throat 116 may define a minimumcross-sectional area of the mixing channel 112 and/or an inflectionpoint in the venturi shape. The diverging section 118 of the venturishape may be positioned downstream of the venturi throat 116. Forexample, the cross-sectional area of the mixing channel 112 may increasemoving axially downstream from the venturi throat 116 over the axiallength of the diverging section 118.

As illustrated in FIGS. 5 and 6 , the fuel inlet 102 may extend axially(e.g., along or parallel to central axis 130 of the igniter 100) suchthat fuel 28 is provided at or near to the venturi throat 116. Forexample, in various embodiments, the fuel inlet 102 may extend to theventuri throat 116 or just upstream of the venturi throat 116 withrespect to the flow of air 26 through the mixing channel 114. In suchembodiments, providing fuel injection at or near the venturi throat 116may advantageously provide an optimal pressure drop where the air 26flowing through the venturi shape will achieve low air pressure and highvelocity at the venturi throat 116, as compared to other portions of themixing channel 114.

In embodiments including the venturi shape, the ignition source 120 maybe positioned downstream of the venturi throat 116. In some embodiments,for example as illustrated in FIG. 5 , the ignition source 120 may bedownstream of the mounting flange 122. In such embodiments, the ignitionsource 120 may be disposed within the combustor 16, e.g., within thehead end 38. In other embodiments, e.g., as illustrated in FIG. 6 , themounting flange 122 may be positioned downstream of the ignition source120, such that the ignition source 120 may be positioned outside of thecombustor 16, e.g., outside of the head end 38, when the igniter 100 ismounted to the end cover 36 of the combustor.

As illustrated in FIG. 5 , embodiments of the igniter 100 include themixing channel 112 defining a venturi shape without the swirler 128. Asillustrated in FIG. 6 , embodiments of the igniter 100 include themixing channel 112 defining a venturi shape in combination with theignition source 120 upstream of the mounting flange. As noted above,features illustrated or described as part of one embodiment may be usedon another embodiment to yield a still further embodiment. Such furtherembodiments may include various combinations of the illustratedfeatures. For example, the cylindrical mixing channel 112 as illustratedin FIG. 3 may also be combined with an ignition source 120 downstream ofthe mounting flange 122, as illustrated in FIG. 5 . As another example,the igniter 100 of FIG. 5 may also include a swirler 128, as illustratedin FIGS. 3 and/or 6 . Also as noted above, each example is provided byway of explanation, not limitation and it is intended that the presentdisclosure covers such modifications and variations as come within thescope of the appended claims and their equivalents.

FIGS. 7 and 8 illustrate another exemplary embodiment of the igniter100. As illustrated in FIG. 7 , fuel conduit 108 may first be in fluidcommunication with a fuel plenum 109 upstream of the mixing plenum 110.For example, the fuel conduit 108 may be in direct fluid communicationwith the fuel plenum 109 via a first fuel inlet 101 and the fuel inlet102, as described above, may be a second fuel inlet in such embodiments.As illustrated in FIG. 7 , in some embodiments, a fuel filter may beprovided in first fuel inlet 101. Accordingly, the fuel conduit 108 maybe in direct fluid communication with the fuel plenum 109 via the firstfuel inlet 101 and in indirect fluid communication with the mixingplenum 110 via the second fuel inlet 102. For example, in suchembodiments, fuel 28 may flow from the fuel plenum 109 through thesecond fuel inlet 102 and into the mixing plenum 110, while air 26 flowsinto the mixing plenum 110 via air conduits 106. Some embodiments mayalso include a second fuel conduit 111 which extends from the fuelplenum 109 into the combustor 16, e.g., through the end cover 36, tosupply fuel 28 to the pilot flame. For example, in some embodiment thepilot flame may emanate from the ejector tube 126. Accordingly, anoutlet 113 of the second fuel conduit 111 may be proximate to an outlet127 of the ejector tube 126. As illustrated in FIG. 8 , the second fuelconduit 111 may be proximate to, and in some embodiments, abutting, theejector tube 126. For example, the ignition source 120 may be positionedin a first portion, e.g., a top portion, of the igniter 100 and thesecond fuel conduit 109 may be positioned second portion, e.g., a bottomportion, diametrically opposite the ignition source. As illustrated inFIG. 8 , in some embodiments, the air inlets 104 may extendcircumferentially around and spaced from the ejector tube 126 betweenthe second fuel conduit 111 and the ignition source 120 (FIG. 7 ).

This written description uses examples to disclose the technology,including the best mode, and also to enable any person skilled in theart to practice the technology, including making and using any devicesor systems and performing any incorporated methods. The patentable scopeof the technology is defined by the claims, and may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they include structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal language of the claims.

What is claimed is:
 1. A combustor comprising: an end cover; a linerdefining a combustion chamber; an outer sleeve spaced apart from and atleast partially surrounding the liner; a head end portion defined by theend cover and the outer sleeve; one or more fuel nozzles extending fromthe end cover through the head end portion to the combustion chamber;and an igniter configured to initiate combustion in the combustionchamber, the igniter comprising: a mixing channel extending axially froma mixing plenum through the end cover and into the combustor withrespect to a central axis of the combustor; a mounting flange extendingdirectly radially outward from the mixing channel, wherein the mountingflange is coupled to the end cover of the combustor; a fuel inlet influid communication with the mixing plenum; an air inlet in fluidcommunication with the mixing plenum; and an ignition source inoperative communication with the mixing channel and disposed outside ofthe head end portion, the ignition source positioned proximate to adownstream end of the mixing channel and upstream of the mounting flangeand the end cover.
 2. The combustor of claim 1, wherein the igniterfurther comprises a swirler downstream of the ignition source.
 3. Thegas turbine combustor of claim 1, wherein the igniter further comprisesa fuel plenum upstream of the mixing plenum and a fuel conduit extendingfrom the fuel plenum, through the end cover, and into the combustor. 4.The combustor of claim 1, wherein the ignition source comprises asparkplug.
 5. The igniter combustor of claim 3, wherein the ignitionsource is positioned at a top portion of the igniter and the fuelconduit is positioned at a bottom portion of the igniter diametricallyopposite the top portion.
 6. The combustor of claim 3, wherein the fuelconduit is entirely parallel to the mixing channel.
 7. A gas turbine,comprising: a compressor; a turbine; a combustor disposed downstreamfrom the compressor and upstream from the turbine, the combustor havingan end cover, a liner defining a combustion chamber, an outer sleevespaced apart from and at least partially surrounding the liner, a headend portion defined by the end cover and the outer sleeve, and one ormore fuel nozzles extending from the end cover through the head endportion to the combustion chamber; and an igniter in operativecommunication with the combustor, the igniter configured to initiatecombustion in the combustion chamber, the igniter comprising: a mixingchannel extending axially from a mixing plenum through the end cover andinto the combustor with respect to a central axis of the combustor; amounting flange extending directly radially outward from the mixingchannel, wherein the mounting flange is coupled to the end cover of thecombustor; a fuel inlet in fluid communication with the mixing plenum,the mixing plenum positioned upstream of the mixing channel; an airconduit extending from the mixing plenum to an air inlet defined on themounting flange; and an ignition source in operative communication withthe mixing channel and disposed outside of the head end portion.
 8. Thegas turbine of claim 7, wherein the mixing channel is cylindrical. 9.The igniter gas turbine of claim 7, wherein the air inlet is one of aplurality of air inlets circumferentially spaced around the mixingchannel.
 10. The gas turbine of claim 7, wherein the combustor is atleast partially surrounded by an outer casing, the outer casing defininga high pressure plenum in fluid communication with the compressor andthe head end portion of the combustor, wherein the ignition source isdisposed outside the high pressure plenum.
 11. The gas turbine of claim7, wherein the air conduit is entirely parallel to the mixing channel.12. The gas turbine of claim 7, wherein the air inlet receives a flow ofcompressed air from the head end portion.